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Timing the Rut

photoBy Bob Humphrey

-- The ingredients were all there for a super hunt. It was the middle of November, peak of the rut, and I was in the heart of big whitetail country. Even the weather was cooperating - clear and cold every day. Now it was all up to the deer.

John Ethridge of PMI Cover Systems met me at Moline Airport in Illinois. John, Dave Dolbee and I drove across into Missouri, where we were to meet our outfitter. Along the way, the guide told us story after story of the big Midwestern bucks he and his hunting partners have taken over the years. I was as excited as a kid on Christmas Eve when I finally settled in for a fitful night's sleep. We'd done all we could. The rest was up to the deer.

I guess someone forgot to tell the deer, because four days later, we were still wondering what went wrong. Timing and conditions seemed perfect, but the big bucks just weren't moving. And it wasn't just us. Every night, John would call his buddies back in Illinois, where he got the same report: no movement. They couldn't understand it. But I had a hunch as to what the matter was.

The classic rut occurs every year around the middle of November, right? That all depends on who you ask. There seems to be a growing schism over when the peak of rut should occur.

One camp believes in the traditional theory that it always occurs at the same time. Another more recent theory says it varies according to moon phase. The latter theory has been gaining a lot more acceptance, and that season provided a significant boost to their contention. Which one is right?  The jury is still out. But let's take a look at the facts. Then you can decide for yourself.

Traditional Rut Theory
Many hunters, and a fair number of biologists, believe that the rut is fairly synchronous, and occurs at roughly the same time every year in northern states, somewhere around Nov. 15-18. Some of the more dedicated hunters even plan their annual hunting vacations then to take advantage of that magical period when mature bucks drop their guard. The biological theory behind this is that rut timing is ruled by daylight, which diminishes at the same rate and time annually. The reasoning here seems fairly sound, as the breeding cycle of many species is triggered by photoperiodism (changes in the amount of daylight).

There is also a large body of scientific evidence to support this theory. Most of it is based on back-dating fetal measurements. Biologists examine unborn fawns in the spring. By measuring certain physical characteristics, they can predict roughly when those fawns were conceived, and they come up with a fairly consistent result. However, this technique has a margin of error of 20 days. That means if fetal measurements produce an estimated conception date of Nov. 15, the actual date could be anywhere from Nov. 5-25.

Moon Phase Theory
A more recent theory, postulated by Charles Alsheimer and Wayne Laroche, suggests that it is not just daylight that stimulates the physiological changes in deer, which eventually lead to rutting behavior. We know that a whitetail's pineal gland responds to changes in the amount of daylight by releasing hormones (estrogen in does and testosterone in bucks), which ultimately triggers the reproductive cycle.

The accepted doctrine was that daylight meant sunlight, and since this varies little from year to year, it seems plausible that the rut should be relatively consistent on an annual basis. However, the moon also produces light.  Furthermore, the period of greatest moonlight varies from year to year depending on when the full moon falls in the calendar year. Laroche noted that the brightest full moons occur in November and December. This theory suggests that, while subtle changes in daylight might be the overriding mechanism, it is the more dramatic changes in moonlight that actually trigger the rut. If this is indeed the case, the rut would not occur at the same time every year.

As it turns out, Alsheimer and Laroche have now amassed more than a decade's worth of data to support their theory. Rather than back-dating fetuses, however, they relied on direct observations of deer during the breeding season. Their observations include both captive and wild deer, and they have several contributors from different areas of the country. What they've found is that the observed peak of rut coincides very nicely with the predicted dates, based on timing of the moon phase.

These researchers also uncovered another interesting fact. Under the moon-phase theory, most does are bred under a dark-moon period. Jumping ahead to an average 199-day gestation period, they calculated that most fawns would then be born within a day of the third-quarter moon. The adaptive advantage of this is obvious. Fawns born during a dark moon phase have a better chance of avoiding or escaping predators.

How Does it Work?
If your interest is piqued, then perhaps you'd like to know how the model actually works. Well, here goes. The onset of the rut, like virtually all other physiological and behavioral changes deer experience throughout the year, is triggered by photoperiodism - the response of an animal to changes in day length. Temperature, weather, hunting pressure, age and sex ratio, and other non-intrinsic factors can influence the level of activity on any given day, but over the long term, it is the length of sunlight and moonlight that is the driving force.

While it cannot be proven as the trigger mechanism, the first round of significant rubbing and scraping usually coincides with October's full moon. This is generally considered the first phase of the rut. Bucks begin scraping prior to the first does coming into estrous. There may be a few hot does, particularly in areas with highly skewed buck-to-doe ratios. But this generality seems to hold true. Then there is a bit of a lull before the next phase.

The next full moon that occurs, the second full moon after the fall equinox, is sometimes referred to as the hunter's moon. It is the rapid decrease in available light following the hunter's moon that triggers hormonal changes in the doe, which eventually incite estrous. Meanwhile, the bucks are primed and ready to breed. The chase phase, which most hunters consider the true rut, usually begins around this time and increases in intensity approaching a 14-day window of peak breeding, which begins around 10 days after the hunter's moon.

This is when you want to be in the woods for trophy bucks. In many cases, the chase phase is the only time during the hunting season mature bucks will expose themselves to potential danger during daylight hours. The rest of the year they're secretive, hiding out during the day and carousing only at night; that's how they get to be big. And what of the rest of the season? If you believe in moon-phase theory, the following can be used as a guideline.

Pre-rut is generally considered a slow period. You'll recall this is the first full moon after the fall equinox. It begins a couple days before the pre-rut moon and ends seven days before the rutting moon. It is still early fall. Temperatures are warm and deer, especially bucks, are less active. They tend to stick to their core areas and move mostly during the cooler hours of twilight and night. The cooling nights however signal to deer that fall and winter are on the way. Feeding intensity picks up and deer change from high-protein summer foods to fall foods that are rich in carbohydrates.

This is the time to hunt food sources, especially those close to bedding cover. You don't want to hunt too close to bedding, however, as you may move deer out of the area completely. You also want to stay away from rut hotspots. According to another whitetail authority, Mark Drury, this is one of the biggest mistakes hunters make.

"Every year I see it," Drury said. "Guys do their scouting, then come the first of October, they're in there hunting their best rut spots.  They burn their stands out because of over-anxiousness.  By the time the rut arrives, every one is used up. Early in the season you can do some afternoon hunting in or near food sources, but save your good stands for the rut."

One advantage of the pre-rut period is that bucks are still traveling in bachelor groups. If you see one there's a good chance others are around. While conventional wisdom says the rut is the best time to rattle, and that may well be true, I've found the pre-rut can be almost as good. Bucks are still in bachelor groups, but this is when they sort out the pecking order. And this is done mostly by sparring. Thus, the sound of clashing antlers is a familiar one. Furthermore, because many bucks are still vying for their position, rattling is more likely to attract subordinate bucks. During the rut, most of the fighting is between dominant rivals of nearly equal stature, and may actually scare off subordinate bucks. There may be a minor flare up of rutting activity as roughly 10 percent of the does come into estrus around the pre-rut moon, but that will subside rapidly.

The Rutting Moon
As you get closer to the hunter's moon, also called the rutting moon, it's time to shift your attention to rut stands. This full moon triggers the hormone production that brings on breeding, with the peak breeding occurring about two weeks after the rutting moon.

This is the time to start keying in on scrapes and rub lines. The bucks are now ready to breed. They begin scraping intensively to advertise this fact to the females, and scrapes become the computer dating service of the whitetail woods. This a perfect time to exploit a dominant buck's jealous nature by introducing a bogus rival. Until the does come into estrus, about the only thing that will draw a mature buck out of hiding is competition. Start applying buck lure to scrape and rub lines right after the rutting moon.

Later in this period, you can start switching to estrous doe lures. Once the does come into heat, bucks begin to lose their wariness, and this will be your best opportunity to tag a mature buck. Rattling works well. The more aggressive the rattling the better. This is another area where hunters often fall short.

Brad Harris, former vice president of public relations for Outland Sports, and host of the cable show "Outdoor Traditions" thinks another big mistake most hunters make is not calling aggressively enough. 

"People are little bit timid," he says. "Maybe they're not totally sold on the effectiveness of calls. They'll carry a grunt call and rattling antlers, maybe use them once or twice and decide they don't work. Or, they'll get a deer to come, then stop calling, thus losing the battle. The deer loses interest and moves off." 

Harris recommends utilizing deer calls aggressively, especially during peak activity periods. "Using natural sounds like grunts, bleats and rattling allows you to cover more terrain and take advantage of upbeat activity patterns than sitting quietly. Bucks are edgy and vulnerable."

Alsheimer also recommends rattling at this time, and hunting transition zones, between bedding and feeding areas. He claims rattling works best from a week before the rutting moon to about the third phase of moon. When a real fight occurs at this time it is almost certain to be two dominant bucks fighting over an estrous doe. Rattling tells a dominant buck that not one, but two potential rivals are battling over his does. Once a buck begins tending a hot doe, about the only thing that will pull him off is a potential rival.

By the time the post-rut period arrives, 80 to 90 percent of the does likely have been bred, and deer have been pressured by hunters for several months. Thus, bucks are worn down from the rut's intensity. Because of this, Alsheimer believes "post-rut bucks can be the hardest of all whitetails to hunt." He recommends hunting food sources close to the thickest cover you can find.

One major advantage northern hunters have is there is often snow on the ground now. Tracking can reveal a lot about movement patterns. A predominance of tracks leading from bedding to feeding likely indicates an afternoon trail, while those leading to bedding often indicate the opposite. Hunters should time their hunts accordingly.

Roughly 28 days after the peak of the first rut, a smaller second rut occurs. This is when most of the remaining does are bred, usually yearling does. This rut is much less intense, and may be barely noticeable. However, by continuing to concentrate on the same cover and doe groups that inhabit it, you'll automatically be putting yourself in the right place. While not as effective as during the first rut, rattling and calling also work now.

Numerous other factors such as weather conditions, temperature and hunting pressure can also wreak havoc on your hunting plans if your goal is to hit the peak of rut. Remember that these are generalities, and for every rule there is an exception. Still, by using the moon phase theory as a guideline, and hunting accordingly, you can increase your chances of scoring big this fall.

By Cam @ Wednesday, November 07, 2007 10:13 AM
If I am doing my calculations right it appears that our "Rutting Moon" will come around November 26th this year. This should be the second full moon after the "Fall Equinox". Again I am basing this on the idea that I am understanding correctly. I would like to know how long of a period of time can we expect these deer to be in this mode? I have seen many "experts" tell us that the peak rut times are somewhere around October 28th-November 14th give or take a couple of days. So our moon phase is more towards the end of the month. What kind of margin of error can we expect?

Also, do these theories apply to all hunting condition? Let me explain. Most of the time I have noticed this activity in more heavily wooded areas or on the edge of a well groomed food plot. My hunting location has some but not a lot of thicket to utilize. It is more over a 120 acre overgrown bean field. All of my stands are located on the woods edge facing fields. I have done my homework, I do know which areas in the morning they travel and which areas in the afternoon the travel. You can almost set your watch by it actually. This particular field was last years crop and no one has planted it this year to say the least it is completely undisturbed.

Now using these theories in the article how does it apply to my situation? Am I doing the right thing by just finding the travel areas or would you recommend something else?

My son and I have great success on our meat hunts, but he is 9 years old and I am waiting for my his first opportunity for that "Wall Hanger".

Thank you all for such wonderul contributions to this sport.

By Steve @ Friday, November 23, 2007 12:28 PM
I read about the Alsheimer / Laroche moon phase theory in "Whitetail Hunting: Tactics of the Pros." It says the 2nd full moon after the fall equinox is the rutting moon. In 2007 the fall equinox was Sept. 23rd and full moons were on Sept. 29th and Oct. 26th, so according to Alsheimer, wouldn't the rut have begun about Oct. 23rd and ended about Nov. 5th? Am I misinterpreting something here? In Michigan in 2007 scrapes were actively tended (cleared of leaves) on Nov. 15th through Nov. 19th, my most recent day in the woods. This does not support the Alsheimer moon-phase theory.

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